Replaceable Wear Tooth Assembly

ABSTRACT

An improved tooth  21  and tooth holder  22  assembly for use with a digging implement such as a post hole digger has a first retention member  23  and a second retention member  24  each of which can be used in isolation or in combination. The first retention member  23  comprises a nylon plug having opposed serrated teeth  25  and which is pushed into an opening in the tooth holder  22 . The tooth contains rigid profiles  26  and when the tooth is pushed into the tooth holder, the serrations and profiles mesh together to positively retain the tooth within the tooth holder. The second retention means  24  comprises a resilient pin. The tooth and the tooth holder have a positive and negative wedge type shape which allows the tooth to be attached in one orientation only.

CROSS REFERENCE TO RELATED APPLICATION

This application takes the benefit of and in turn claims priority under35 USC §119 to Australian Provisional Patent Application No. 2015901525filed on 29 Apr. 2015, the contents of which are herein incorporated byreference.

TECHNICAL FIELD

The present invention is directed to a replaceable wear tooth assemblyfor a ground digging tool such as a hole digging screw auger an exampleof which is a post hole digger. Other ground digging tools such as adigging bucket may also benefit from the replaceable wear toothassembly.

BACKGROUND

Any references to methods, apparatus or documents of the prior art arenot to be taken as constituting any evidence or admission that theyformed, or form part of the common general knowledge.

Current practice is that ground engaging tools/wear parts are utilisedas consumables and are required by their nature to be replaceable. Anexample of this type of use is a screw auger that utilises replaceablewear teeth.

Similarly, an excavator bucket, and typically a digging bucket, utilisesreplaceable teeth on the leading edge.

The purpose of these consumable items is to engage the earth andpreferentially wear out to avoid premature damage to the main body ofthe digging implement. By replacing the teeth, an optimum cutting edgecan be maintained.

In the case of a screw auger, the teeth become sacrificial items asopposed to the screw auger itself. In the case of a bucket the teeth onthe leading edge are sacrificed as opposed to the main body of thebucket.

An example of an auger is a post hole digger. The auger is usually topmounted to a hydraulic motor which rotates the auger.

FIG. 1 illustrates a hole digging auger which comprises a shaft 11 longenough for the hole to be dug, a helical screw (also called a “flight”)12 welded to the outside of the shaft, a lower extending head plate 13,a lowermost point (a pilot) 14 and a number of digging teeth 15. The topof the shaft 11 has a mounting 16 to enable it to be connected to androtated by a motor.

The auger can be mounted to a petrol motor and be a one person or twoperson auger, these devices being suited for smaller jobs.

For larger jobs, the auger is usually driven by a hydraulic motorsupported by a bob cat or other machine.

The teeth are subject to large loads and high abrasion as they arecontinuously exposed to the elements and high wear environments. Theloads apply force to the tooth and attempt to force the tooth into themain body of the screw auger, and cause large amounts of friction on thefrontal part of the tooth and high wear on these items is a result.

The teeth are susceptible to wear and tear and need to be replaceable.Thus it is known to provide replaceable teeth for an auger. The headplate is typically provided with tooth holders and digging teeth can beremoveably mounted to the tooth holders.

It is known to use a steel retaining pin to hold the tooth to the toothholder. The pin can be hammered out to release the tooth from theholder. However it is known that the pin can be bent or deformed whenthe auger strikes a rock or digs into very heavy earth etc., as thistransmits an extremely high “shock load” or peak load to the pin. A bentor deformed pin can be difficult to hammer out, and in extreme cases mayneed to be drilled out. This is a serious disadvantage.

Thus it is known to provide rubber inserts at places between the toothand the holder to absorb these peak loads and reduce damage to theretaining pin. A disadvantage with this arrangement is in the correctplacement of these inserts and ensuring that the inserts remain in placeduring use of the auger. The inserts are separate items that need to beinspected and possibly replaced and increases the complexity of thetooth holder assembly. For smaller teeth and holders, the inserts needto be smaller and may not be sufficient to properly absorb peak loads.

There would be an advantage if it were possible to retain a tooth in atooth holder using a pin but without requiring the use of separateresilient inserts to prevent damage to the pin.

It is known to attach teeth to teeth holders without using a steelretaining pin. Thus it is known to use rubber cord or rubber strips orrubber friction members to jam the tooth in the tooth holder. The rubberfrictionally engages the tooth to hold the tooth in the holder. Thisarrangement suffers from disadvantages when a negative force (or a“pulling” force) is applied to the tooth. For instance a sufficientlystrong negative force on the tooth can cause the rubber friction membersto fail and for the tooth to be inadvertently pulled out of the holder.

In the case of digging augers, when pulling auger out of the hole,forces applied in the opposite direction can easily overcome thefriction required to retain the tooth when using rubber only as theretention technique. The result of this is the wear tooth is dislodgedfrom its holder and falls to the bottom of the hole and can beun-retrievable. This is a serious disadvantage.

Furthermore, if the auger becomes stuck in use, the drive unit on top ofthe auger is capable of reverse function to unstick or dislodge theauger from the spoil. This reverse function can apply a strong negativeor “pulling” force on the wear tooth and can cause the tooth to bepulled out of its holder. The potential for dislodgement on thisscenario of reversing the screw auger utilising rubber frictionretention is very high. This is a serious disadvantage.

There would be an advantage if it were possible to attach a tooth to atooth holder in a manner to prevent the tooth from becoming detachedwhen subjected to a negative force.

Another disadvantage with many tooth and tooth holder assemblies is therequirement to use specialist tools and equipment to remove the toothfrom the holder. For teeth held in place with a steel retaining pin, apin removing tool is required. When the pin is removed, the tooth isoften still held in the holder by contact with the walls of the holder,attached debris, some damage to the tooth, and the like. The tooth thenneeds to be forced out of the holder.

Conventionally, specifically manufactured wedges are used to force thetooth out of the holder. The wedges are hammered into position and thiscan damage the tooth and holder. Operators will also attempt to ram anyimplement in between the wear tooth and tooth holder and in any cavityavailable and this can also damage the holder and tooth. This operationis also applicable to remove a tooth from the holder when a retainingpin is not present.

There would be an advantage if it were possible to remove a tooth from aholder without specialist equipment and without inadvertent damage tothe holder and tooth.

It is an object of the invention to provide a replaceable wear toothassembly which could overcome at least one of the abovementioneddisadvantages or provide a useful or commercial choice in themarketplace.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided areplaceable tooth assembly for an auger, the assembly comprising atooth, a tooth holder, a first retention member to retain the tooth inthe holder and a separate second retention member to retain the tooth inthe holder,

the first retention member adapted to be mounted to the holder andcomprising a plurality of resilient members,

the tooth comprising a plurality of rigid profiles adapted to engagewith the resilient members to retain the tooth to the holder,

the second retention member comprising a removable pin.

In this manner a tooth can be mounted to its tooth holder using tworetaining members, each member being able to resist a negative or“pulling” force on the tooth. The first retaining member locks the toothby forcing the resilient members into engagement with the rigid profileson the tooth. The second retaining member is a removable pin.

To remove the tooth, the pin is removed and the tooth is knocked out ofthe holder with sufficient force to deform the resilient members toenable the rigid profiles on the tooth to ride past the resilientmembers to free the tooth from the holder.

FIG. 2 illustrates a non-limiting embodiment of a tooth 21 which istypically formed from steel and has rigid steel profiles 26.

FIGS. 3 and 4 illustrate a non-limiting embodiment of a tooth holder 22with FIG. 4 (a partially cut away view of FIG. 3) particularlyillustrating an internal wall 28 having an opening 29 in which the firstretaining member 23 can be fitted. A non-limiting embodiment of thefirst retaining member is illustrated in FIG. 8.

The tooth 21 can be pushed or hammered into the holder until theprofiles on the tooth engage with the members on the first retainingmember.

The replaceable tooth assembly finds particular suitability for use witha digging auger such as a posthole digger as this type of tool can besubject to negative or pulling forces. However, the replaceable toothassembly may also be suitable for use with digging buckets or any othertype of engaging tool that can benefit from this type of assembly.

The tooth is typically made from hard rigid material. This material maycomprise forged steel, hardened tool steel, high quality alloy steelheat treated to offer maximum resistance to wear and impact, cast ironmade from a heat treated ductile iron and the like. The teeth may beforged, cast or fabricated.

The size of the tooth can vary depending on the digging implement towhich the tooth is attached. For use with a posthole digger auger, it isconsidered that the tooth will have a length of between 1-4 inches and awidth of between 0.75-2 Inches. For use with a larger digging bucket, itis envisaged that the size of the tooth will be larger.

Suitably, the tooth will comprise a front portion and a rear portion.The front portion will typically comprise or include the leading edge ofthe tooth. The leading edge may be treated to improve hardness and thismay include hard facing and the like. The front portion of the tooth maybe substantially rectangular when viewed in plan. The front portion ofthe tooth may be tapered when viewed in side elevation from a thickerrear portion to a thinner leading edge.

The rear portion of the tooth may be bifurcated when viewed in plan andtherefore may comprise a first leg portion and a second leg portion.

At least one (and preferably both) leg portions may include the rigidprofiles adapted to engage with the resilient member to retain the toothto the tooth holder. The rigid profiles are preferably located on innerwalls of each leg portion.

The rear portion may include a configuration to allow the tooth to beinserted into the holder in only one orientation. The configuration mayinclude at least one abutment or wedge which will prevent the tooth frombeing fully inserted and retained in the wrong orientation (for instanceupside down).

The rear portion may include a pin retention means to enable a retainingpin to hold the tooth in the tooth holder. The pin retention means maycomprise a recess. The recess may comprise a semicircular recess adaptedto locate approximately half the circumference of the retaining pin. Therecess may be located on one of the leg portions.

The tooth holder is typically adapted to be permanently fixed to thedesired type of tool. If the tool is an auger, the tooth holder willtypically be welded or otherwise permanently fixed to the head plate(see for instance reference numeral 13 in FIG. 1) of the auger.

The tooth holder suitably comprises a solid rear portion/wall, and a topwall and a bottom wall extending from the rear portion/wall. The toothholder can therefore have a somewhat C shaped configuration when viewedin side elevation. The top wall and the bottom wall are typically spacedapart by a distance sufficient to enable the rear portion of a tooth tobe positioned between the top wall and the bottom wall. It is thereforeenvisaged that the spacing between the top wall and the bottom wall willtypically be between 5-30 mm.

The top wall and the bottom wall may be somewhat rectangular when viewedin plan. The size of the tooth holder will vary depending on the size ofthe tooth and the size and type of tool to which the tooth holder willbe attached. It is envisaged that the top wall and the bottom wall willtypically have a length of between 1-4 inches and a width of between8-30 Inches although this can vary and it is not considered that anyparticular limitation should be placed on the invention merely byexemplification of certain sizes of the tooth holder.

The tooth holder will typically be manufactured from a strong rigidmaterial such as steel and alloys of steel.

One wall of the tooth holder may be provided with an abutment or step orwedge type configuration adjacent a rear portion of the wall, a purposeof this being to ensure that the tooth is positioned to the tooth holderin the correct orientation and this will be described in greater detailbelow.

The tooth holder will suitably contain an internal wall extendingbetween the top wall and the bottom wall. The internal wall may have aforward curved configuration.

An opening may be provided through the internal wall. The opening willtypically provide a location or mounting area for the first retentionmember. The opening may have a configuration to hold the retentionmember in a particular orientation. The opening may have a configurationto prevent the retention member from rotating in the opening. Theopening may therefore comprise a somewhat keyhole shaped opening.

The tooth holder may include some form of means to assist in the removal(knocking out) of the tooth from the tooth holder. The means maycomprise a knockout recess. The knockout recess may be provided in afront portion of the top wall and/or the bottom wall and it is preferredthat the top wall and the bottom wall contain a knockout recess. Theknockout recess may be substantially U-shaped when viewed in plan.

The tooth holder may include at least one opening to accommodate asecond retention member. Suitably, the top wall and/or the bottom wallcontain an opening aligned or otherwise arranged to enable a retentionmember to pass through or at least into the openings. As it is envisagedthat the second retention member will comprise a pin, it is envisagedthat the openings will be aligned.

The first retention member functions to retain the tooth in the toothholder. The first retention member is preferably a separate member whichis fixed to the tooth holder and which can hold the tooth in the toothholder. The first retention member includes a plurality of resilientmembers to assist in holding the tooth in the tooth holder.

Suitably, the tooth holder includes an internal wall with an opening andthe first retention member extends through the opening and is mounted tothe tooth holder by the opening.

The first retention member may comprise a solid plug like body. The pluglike body may have a shape that prevents the retention member frominadvertent rotation in the opening, and also correctly orientates theresilient members on the first retention member. Suitably, the body mayhave a cross-section consisting of a larger circle joined by a smallersemicircle such that the body can fit within a keyhole type of opening.Of course, it is envisaged that the body and opening may have othershapes and configurations to ensure that the first retention member islocated on the tooth holder in the correct orientation.

The plug like body may include opposed end faces. At least one andpreferably both of the end faces contain the resilient members.

The resilient members may be formed integrally with the body or may beformed separately and attached to the body by any suitable means.

If the resilient members are formed integrally with the body, it isenvisaged that the body will comprise a resilient material such as anylon, a rubber, a neoprene, resilient composite materials and the like.

An advantage with the body being formed of resilient material is thatthe body can also be fixed in the opening by friction engagement betweenthe outer wall of the body and the inner wall of the opening.

However, it is also envisaged that the body may be formed of rigidmaterial such as a hard plastic and the resilient members can be coextruded onto the body, or formed separately and attached to the body byadhesive, plastic welding or other suitable means.

The resilient members may comprise an array of teeth. The teeth maycomprise separate elongate tooth like ridges or may comprise an array ofseparate button like projections.

A second retention means may be provided to further retain the tooth onthe holder. The second retention means suitably comprises a removablepin. The removable pin may comprise resilient or plastic material. Theresilient material may comprise nylon, rubber, neoprene, compositematerials and the like.

In a second aspect of the invention there is provided a replaceabletooth assembly for an auger, the assembly comprising a tooth, a toothholder, and a first retention member to retain the tooth in the holder,the first retention member adapted to be mounted to the holder andcomprising a plurality of resilient members the tooth comprising aplurality of rigid profiles adapted to engage with the resilient membersto retain the tooth to the holder.

The tooth, tooth holder, and first retention member may be as describedabove.

In this aspect of the invention, a second retention member is notprovided.

In a third aspect of the invention there is provided a replaceable toothassembly for an auger, the assembly comprising a tooth, a tooth holder,and a retention member in the form of a resilient removable pin toretain the tooth in the holder,

-   a. the tooth holder comprising an top wall, a bottom wall and an    internal wall connecting the top wall and the bottom wall,-   b. an opening through the top wall adapted to accommodate the pin,-   c. the tooth having a rear portion adapted to pass into the tooth    holder and between the top wall and bottom wall, and,-   d. pin retention means on the rear portion of the tooth adapted to    retain the tooth to the holder when the pin is inserted.

In this aspect of the invention, the design of the holder and toothenables the pin to be resilient. This pin thus functions to retain thetooth to the holder and can also accommodate peak forces without bendingor damage to the pin of the type that makes removal of the pindifficult. No additional separate shock absorbing pads or inserts arerequired making the assembly simpler and easier in use.

In a fourth aspect of the invention there is provided a replaceabletooth assembly for an auger, the assembly comprising a tooth, and toothholder, the tooth comprising a rear portion adapted for insertion intothe tooth holder, the rear portion comprising a configuration to allowthe tooth to be inserted into the holder in only one orientation, and atleast one retention means to retain the tooth to the holder.

In this aspect of the invention the tooth may be hard faced on only onesurface which will dig into the ground. This can save on cost. The toothcan then be inserted into the holder in one orientation only which isthe orientation that ensures that the hard face is in the correctposition. That is, the tooth cannot be inserted and locked to the holderwhen in the inverted position.

The configuration may comprise an abutment or wedge which prevents thetooth from being correctly inserted when in the wrong orientation.

In a fifth aspect of the invention there is provided a removable toothfor an auger, the tooth adapted to be attached to a tooth holder on theauger, the tooth comprising a leading edge adapted for ground engagementand a rear portion adapted for insertion into the tooth holder, the rearportion being bifurcated and comprising a first leg portion and a secondleg portion, at least one leg portion comprising rigid profiles adaptedto engage with resilient members on a retaining member to retain thetooth to the holder.

The tooth may include a configuration to allow the tooth to be insertedinto the holder in only one orientation. The configuration may be asdescribed above.

The tooth may include pin retention means on the rear portion of thetooth adapted to retain the tooth to the holder when a retaining pin isinserted.

The tooth may include a knock out point to give a purchase for anexternal instrument to knock the tooth out of the tooth holder.

In a sixth aspect of the invention, there is provided a retention memberto enable a wear tooth to be removably attached to a tooth holder, theretention member comprising a plug like body having opposed faces, leastone said face comprising resilient members.

The retention member may be as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred features, embodiments and variations of the invention may bediscerned from the following Detailed Description which providessufficient information for those skilled in the art to perform theinvention. The Detailed Description is not to be regarded as limitingthe scope of the preceding Summary of the Invention in any way. TheDetailed Description will make reference to a number of drawings asfollows:

FIG. 1. Illustrates a digging auger generally of known design butcontaining tooth holders and teeth according to preferred embodiment ofthe invention.

FIG. 1A. Illustrates a tooth attached to a tooth holder.

FIG. 2. Illustrates a plan view of a tooth according to a preferredembodiment of the invention.

FIG. 2A. Illustrates a side elevation view of the tooth of FIG. 2.

FIG. 3. Illustrates a tooth holder according to a preferred embodimentof the invention.

FIG. 4. Illustrates a partially cutaway tooth holder of FIG. 4 to enablethe internal wall (28) and the opening (29) in the internal wall to bebetter illustrated.

FIG. 5. Illustrates a side elevation view of the tooth holder of FIG. 3.

FIG. 6. Illustrates a plan view of the tooth holder of FIG. 3.

FIG. 7. Illustrates schematically a first retention member and a secondretention member attached to a tooth (but omitting the surrounding toothholder).

FIG. 8. Illustrates the first retention member according to a preferredembodiment of the invention.

FIG. 9. Illustrates the second retention member according to a preferredembodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to the figures, there is depicted a replaceable tooth assembly20 for an auger 10, the assembly comprising a tooth 21, a tooth holder22, a first retention member 23 to retain the tooth in the holder and aseparate second retention member 24 to retain the tooth in the holder,

-   a. the first retention member adapted to be mounted to the holder    and comprising a plurality of resilient members 25,-   b. the tooth 21 comprising a plurality of rigid profiles 26 adapted    to engage with the resilient members to retain the tooth to the    holder,-   c. the second retention member 24 comprising a removable pin.

Auger 10 may be as illustrated in FIG. 1, but it should be appreciatedthat the tooth assembly need not be limited to this type of auger andthere may be circumstances where the tooth assembly can be used on otherground engaging implement such as excavator buckets and the like.However, for the purposes of the detailed description of a preferredembodiment of the invention, reference will be made to auger 10.

The auger 10 conventionally includes a steel shaft 11 which has a lengthdepending on the depth of the hole which is to be dug. Welded to shaft11 is a steel flight 12. At the lower end of auger 10 is a head plate13. Longitudinally aligned with steel shaft 11 is a pilot 14 which canalso be a replaceable member but pilot 14 does not form part of thepresent invention and may be a conventional piece. The other end ofshaft 11 contains a conventional type of mounting 16 typically to enablethe auger to be attached to and rotated by a hydraulic motor whichitself is typically attached to a bob cat arm or another type ofmachine.

The head plate 13 is provided with a plurality of tooth holders 22. Eachtooth holder is welded or otherwise fixed to head plate 13. A diggingtooth (hereinafter called a tooth) is releasably attached to each toothholder. Thus, when the digging tooth becomes damaged or dull, it can bereplaced. The teeth can also be quickly replaced if the groundcomposition changes.

Referring now to FIGS. 3-6 and particularly to FIG. 3 and FIG. 4, thereis illustrated a tooth holder according to an embodiment of theinvention. The tooth holder 22 is made from steel. A rear portion 40 ofthe tooth holder is welded or otherwise fixed to the head plate 13 ofthe auger. The tooth holder comprises a thick steel top wall 30 and athick steel bottom wall 31 which are interconnected to the rear portion14. The entire tooth holder can be fabricated as a single piece.

An interconnecting steel internal wall 28 extends between top wall 30and bottom wall 31. Internal wall 28 is best illustrated in FIG. 4 whichshows a partially cutaway tooth holder with the top wall 30 of the toothholder being partially cutaway to better illustrate the internal wall28. Internal wall 28 is approximately midway between the sidewalls oftop wall 30 and bottom wall 31. Internal wall 28 also extends fromapproximately a front end of top wall 30 and bottom wall 31 to the rearportion 40.

Internal wall 28 has a forward curved configuration 42 (partiallyvisible in FIG. 3) to match a recess 55 in tooth 21 and this will bedescribed in greater detail below.

An opening 29 is provided in wall 28. The function of opening 29 is tolocate the first retention member 23 and this will be described ingreater detail below. Opening 29 has a particular somewhat keyhole typeconfiguration the reason for which is to prevent unwanted rotation ofretention member 23 when the retention member is located within theopening.

The free forward end of top wall 30 and bottom wall 31 is provided witha notch or recess 44 which is a knockout recess to make it easier forthe tooth to be knocked out of the tooth holder without the requirementsof any specialty tools and this will be described in greater detailbelow. The recess corresponds to the knock out point 47 located on thewear tooth. This allows for an implement to knock the tooth out whenchanging.

Top wall 30 is provided with an opening (retaining pin recess) 45 toaccommodate the locking pin (the second retention member 24). Bottomwall 31 will also include a similar aligned opening.

Top wall 30 is provided with a welding point locator 49 embedded In thetooth casting to allow quick and accurate alignment of the tooth holderto the head plate 13 of the auger 10.

Bottom wall 31 has a stepped wedge like configuration 41 at a rearportion of the bottom wall and the function of this is to prevent aspecially shaped tooth 21 from being inserted the wrong way round intothe tooth holder. This will be described in greater detail below.

Referring to FIG. 8, there is illustrated the first retention member 23.Member 23 is substantially plug like in configuration and in theparticular embodiment is manufactured from nylon and therefore can alsobe seen as a nylon retainer. Member 23 has a particular configurationand in cross-section consists of a larger circle 50 joined by a smallersemicircle 51. The cross-section shape of member 23 compliments theparticular shape of the opening 29 extending through the internal wallof 28 of the tooth holder 22. Member 23 can therefore be pushed intoopening 29 and the size of member 23 is such that the outer wall of themember gripps against the internal wall of opening 29 to firmly locatethe member in place. The particular shape of member 23 and opening 29 issuch to prevent the member from rotating or turning within the opening.Thus, the member is not entirely circular in design.

Each opposed end face of member 23 contains resilient members 25 whichin the particular embodiment comprises an array of serrations or teeth.In the particular embodiment, the resilient members 25 are formedintegrally with the member and are therefore made of nylon. The shapeand configuration of the resilient members 25 are such that they canslightly deform or be pushed to one side upon insertion of tooth 21 andthis will be described in greater detail below.

It can be seen that the orientation of the resilient members 25 and theshape of member 23 is such that when the member is pushed into opening29 of the tooth holder 22, the serrations will all be substantiallyvertical (if the tooth holder is held in a horizontal position) and beslightly proud of the opening 29.

Referring now to FIG. 2 and FIG. 2A, there is illustrated a tooth 21according to a preferred embodiment of the invention. Tooth 21 is formedfrom strong steel and comprises a front portion 33 containing theleading edge 37 and comprises a rear portion 32. The rear portion 32(see particularly FIG. 2) is bifurcated and therefore defines a firstleg portion 34 and a second leg portion 35. The recess 52 definedbetween the leg portions has a forward curved configuration and thisrecess 52 is designed to complement the outer shape of the internal wall28 of the tooth holder such that the tooth can fit snugly into the toothholder with each leg portion 34, 35 extending along each opposed side ofinternal wall of 28 of the tooth holder without unnecessary sidewaysrocking movement.

The leading edge 37 forms the initial point of contact with the groundand this edge can be hard faced or have tungsten inserts to prolongtooth life.

A knockout notch 47 is provided in tooth 21 and generally in the area inthe joining between the leg portions. Notch 47 is designed to align withthe knockout recess 44 in the tooth holder (see for instance FIG. 3)when tooth 21 is in place. This makes it relatively easy to knock outthe tooth from the tooth holder and against the force of the resilientmembers 25 on the first retention member 23 and this will be describedin greater detail below.

The inner wall of each leg portion 34, 35 is provided with rigidprofiles 26 in the form of inwardly pointing serrations. Theseserrations are formed integrally with tooth 21 and as tooth 21 is formedfrom steel, the serrations will also be rigid steel serrations.

One of the leg portions (in the embodiment leg portion 35) contains apin retention means in the form of a recess 38. Recess 38 engages withpart of the second retention member 24 to assist in locking the tooth 21to the tooth holder 24 and this will be described in greater detailbelow.

FIG. 2A illustrates tooth 21 in side elevation and it can be seen thatthe front portion 33 tapers from a thinner leading edge 37 to a thickermiddle portion. FIG. 2A also illustrates in side elevation leg portion35. Leg portion 35 (and also leg portion 34) contains an abutment orwedge 36. This wedge acts as a locating shape to prevent the tooth 21being inserted into the tooth holder in an inverted position. Morespecifically, and referring to FIG. 3 as well as FIG. 2A, it can be seenthat the rear portion of bottom wall 31 in the tooth holder (see FIG. 3)also contains an abutment or wedge arrangement 41 and the shape of thiswedge arrangement 41 and wedge 36 on the tooth 21 is such that the tooth21 can only be inserted correctly in one orientation. If the tooth isattempted to be inserted “upside down”, into the tooth holder, the toothcannot be fully inserted into the tooth holder and therefore cannotengage with the first retention means 23 and a second retention means24.

To insert tooth 21 into tooth holder 22, tooth 21 is initiallypositioned in the correct orientation to ensure that the leading edge 27is correctly orientated. Tooth 21 is then pushed into tooth holder 22such that the internal wall of 28 of the tooth holder 22 extends betweenleg portions 34 and 35 of tooth 21. At some stage, the hard steelprofiles 26 on the internal wall of each leg member 34, 35 will contactthe resilient members/teeth 25 on the first retention member 23 which islocated in opening 29 on internal wall of 28. A resistance will then benoticed. The tooth 21 is then pushed further into the tooth holder andit may be necessary to use a hammer or something similar. This furtherpushing will cause the inwardly pointing serrations/profiles 26 on eachleg portion 34, 35 to push into and deform the resilient teeth 25 on thefirst retention member 23. Additionally, the abutment/wedge 36 on theend of each leg portion 34, 35 can fit into the abutment/wedge portion41 in the rear of the tooth holder. When the end of each leg portion 34,35 abuts against the innermost wall 53 (see FIG. 3), the tooth is fullyin place.

In this position, the hard steel inwardly pointing serrations/profiles26 have meshed into the resilient members/teeth 25 on the nylon firstretention member 23. This provides a positive retention of the tooth inthe tooth holder and it is difficult to easily pull the tooth out of thetooth holder against the positive retention caused by theinter-engagement of the steel profiles 26 in between the resilientmembers/teeth 25.

To remove the tooth, it is necessary to use a knockout tool which can beplaced in the knockout notch 47 on the tooth (which is aligned with theknockout recess 44 on the tooth holder). Use of the knockout tool willforce the hard steel profiles 26 to ride back over the resilient membersuntil such time as the tooth is released. It should be appreciated thatthe inwardly pointing orientations of the hard steel profiles 26 (seeFIG. 2) will make it easier to insert the tooth into the tooth holderand will make it quite difficult to inadvertently remove the tooth fromthe tooth holder.

FIG. 7 illustrates schematically a tooth 21 positively inter-engagedwith the resilient members on the first retention member 23.

When the tooth is in the fully inserted position, the pin retentionmeans 38 on leg portion 35 aligns with the opening 45 in the toothholder (see FIG. 3). This enables a second retention member in the formof a pin 24 to pass through opening 45 and through pin retention means38 to further positively retain the tooth in the tooth holder.

An example of a pin is illustrated in FIG. 9. In the embodiment, the pinis a nylon retaining pin. The pin contains a chamfer 54 to allow the pinto seat home in the correct position on the tooth holder, the opening 45in the tooth holder also containing a chamfer containing a recess toprovide a flush finish. This prevents any damage to the head of the pinduring use.

To remove the tooth, the nylon retaining pin is knocked out. Thereafter,a simple non-specific knockout tool can be inserted into the knockoutrecess 44 to engage with the knockout notch 47 on the tooth and thetooth can be knocked out against the positive force of the steelprofiles 26 engaging or intermeshing with the resilient members 25.

The first retention member 23 containing the resilient members 25 is areplaceable item and when worn, can be easily removed and replaced witha new retention member. Similarly, the second retention member can alsobe easily replaced.

The assembly utilises a positive retention technique through the use ofpositive retention nylon composite or similar compound retainer(s) 23,24. The first (middle) retainer 23 will be inserted into the internalwall 28 of the tooth holder, and will lock into place by recesses in thetooth holder and corresponding serrated recess in the wear tooth. Oncelocked in place the tooth 21 cannot be unintentionally dislodged due tothe shape of the retainer.

The invention also intends to apply a competitive choice to the marketby utilising a rear retaining pin 24 as a secondary retention technique.This rear retaining pin will also be a nylon composite material, notsteel. The use of this composite nylon avoids the requirement to utiliseguide rails and rubber wedges as shock absorbers.

Both retention members 23, 24 can work independently of each other toretain the wear tooth in the tooth holder. However when working togetherin the one system it provides a superior lock.

The nylon retention members 23, 24 are an economical consumable product.

This retention assembly allows the replacement of teeth 21 with nospeciality tools. The tooth itself can be removed from the tooth holderwith any pointed tool as a wedge and with the assistance of the knockout points 44.

The design prevents unwanted dislodgement of the wear tooth whennegative pressure is applied in the form of reverse capability andpulling out.

The nylon positive retention members 23, 24 will positively lock thetooth into the tooth holder so that when negative pressure is appliedthrough drilling, the tooth will not dislodge.

The resilient nature of the retention members 23, 24 and their designallows for flex at peak loading when the teeth engage the ground. Thefirst (middle) retention member 23 still gives high retention and doesnot encounter any problems associated with peak loading or twisting.This retainer on its own will give reversible capabilities but when atooth is required to be replaced the retainer and tooth can be easilyremoved.

The composition of the second (rear retainer) being a nylon likematerial composite and not steel also allows it flex under load andforegoes any requirement to have guide rails or shock absorbing wedgesto avoid the pin bending. The rear pin aids in the retentioncapabilities and on its own will retain the wear tooth with reversingcapabilities. The ability to have both systems work independently givescompetitive choice and ability to be interchangeable with other systems.

The wedge shaped design on the rear of the tooth allows the tooth to beinserted in one way. Current practice by some other manufacturers is toprovide a rubber friction retainer, but this allows the wear tooth to beinserted in either direction. The problem this creates is that thespecific hard facing/tungsten tip on the tooth is placed in an invertedposition. This can mean the tungsten or hard facing is no longer theleading edge engaging the earth and will wear prematurely and not havefull benefit of the hard facing. The wedge shaped design on the rear ofthe tooth takes away any ability to insert the wear tooth in an invertedposition. If the tooth is accidently inserted upside down, the toothwill not fully seat home and engage either of its retainers 24, 25. Theoperator will have a clear view that the tooth is not correctly seatedif placed in the wrong way.

Prior Art tooth and holder design causes the entire load that is appliedon the wear tooth to be transferred directed through the U-Shape of thewear tooth and corresponding central point in the tooth holder. This cansee premature wear applied to this area. The wedge shaped design on therear of the tooth gives a secondary benefit in that is disperses theload and spreads it between the U-Shape and both legs of the wear toothgiving prolonged wear tooth life.

The knockout points 44, 47 embedded into the tooth and tooth holderallow for quick interchangeability. Prior Art designs requirespecifically manufactured wedges used to force the wear tooth out of thetooth holder. It also allows an operator to attempt to ram any implementin between the wear tooth and tooth holder in any cavity available. Theknockout points 44, 47 embedded into the tooth and tooth holder giveclear and safe points that the user can insert a punch or similar toknock the wear tooth out of the tooth holder in an effective andefficient manner. The knockout points that are designed for that purposeand allow for wear tooth removal without specifically manufacturedtooling.

The above description identifies at least one specific, substantial andcredible use for the invention. In particular, the specificationdescribes an improved tooth and tooth holder assembly which uses a firstretention member and a second retention member each of which can be usedin isolation or in combination and provides a means to prevent the toothfrom being inserted the wrong way round into the tooth holder.

In compliance with the statute, the invention has been described inlanguage more or less specific to structural or methodical features. Theterm “comprises” and its variations, such as “comprising” and “comprisedof” is used throughout in an inclusive sense and not to the exclusion ofany additional features. It is to be understood that the invention isnot limited to specific features shown or described since the meansherein described comprises preferred forms of putting the invention intoeffect. The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted by those skilled in the art.

Throughout the specification and claims (if present), unless the contextrequires otherwise, the term “substantially” or “about” will beunderstood to not be limited to the value for the range qualified by theterms.

Any embodiment of the invention is meant to be illustrative only and isnot meant to be limiting to the invention. Therefore, it should beappreciated that various other changes and modifications can be made toany embodiment described without departing from the spirit and scope ofthe invention.

We claim:
 1. A replaceable tooth assembly for an auger, the assemblycomprising a tooth, a tooth holder, a first retention member to retainthe tooth in the holder and a separate second retention member to retainthe tooth in the holder, the first retention member adapted to bemounted to the holder and comprising a plurality of resilient members,the tooth comprising a plurality of rigid profiles adapted to engagewith the resilient members to retain the tooth to the holder, the secondretention member comprising a removable pin, whereby the first retainingmember locks the tooth by forcing the resilient members into engagementwith the rigid profiles on the tooth.
 2. An assembly according to claim1, wherein the tooth comprises a front portion and a rear portion with aleading edge of the tooth located on the front portion.
 3. An assemblyaccording to claim 2, wherein the front portion of the tooth isrectangular when viewed in plan and tapered when viewed in sideelevation from a thicker rear portion to a thinner leading edge.
 4. Anassembly according to claim 2, wherein the rear portion of the tooth isbifurcated when viewed in plan and comprises a first leg portion and asecond leg portion.
 5. An assembly according to claim 4, wherein the legportions include the rigid profiles adapted to engage with the resilientmember to retain the tooth to the tooth holder.
 6. An assembly accordingto claim 5, wherein the rigid profiles are located on inner walls ofeach leg portion.
 7. An assembly according to claim 2, wherein the rearportion includes a configuration comprising at least one abutment orwedge to allow the tooth to be inserted into the holder in only oneorientation.
 8. An assembly according to claim 4, wherein the rearportion includes a pin retainer to enable a retaining pin to hold thetooth in the tooth holder.
 9. An assembly according to claim 8, whereinthe pin retainer comprises a semicircular recess adapted to locateapproximately half the circumference of the retaining pin.
 10. Anassembly according to claim 9, wherein the recess is located on one ofthe leg portions.
 11. An assembly according to claim 1 in combinationwith an auger wherein the tooth holder is permanently fixed to theauger.
 12. An assembly according to claim 1, wherein the tooth holdercomprises a solid rear wall, and a top wall and a bottom wall extendingfrom the rear wall.
 13. An assembly according to claim 12, wherein thetop wall and the bottom wall are typically spaced apart by a distancesufficient to enable a rear portion of a tooth to be positioned betweenthe top wall and the bottom wall.
 14. An assembly according to claim 13,wherein one wall of the tooth holder includes an abutment or step orwedge type configuration adjacent a rear portion of the wall to ensurethat the tooth is correctly orientated in the tooth holder.
 15. Anassembly according to claim 12, wherein the tooth holder has an internalwall extending between the top wall and the bottom wall.
 16. An assemblyaccording to claim 15, wherein an opening is provided through theinternal wall for locating the first retention member.
 17. An assemblyaccording to claim 16, wherein the opening is keyhole shaped.
 18. Anassembly according to claim 1, wherein the tooth holder includes aknockout recess to assist in removal of the tooth.
 19. An assemblyaccording to claim 1 wherein the tooth holder includes at least oneopening to accommodate a second retention member.
 20. An assemblyaccording to claim 1 including a plurality of resilient members toassist in holding the tooth in the tooth holder.
 21. A removable toothfor a replaceable tooth assembly for an auger, the tooth adapted to beattached to a tooth holder, the tooth comprising a leading edge adaptedfor ground engagement and a rear portion adapted for insertion into thetooth holder, the rear portion being bifurcated and comprising a firstleg portion and a second leg portion, at least one leg portioncomprising rigid profiles adapted to engage with resilient members on aretaining member to retain the tooth to the holder.